Pneumatic nut-runner having a torque sensing device

ABSTRACT

A torque sensing device is attached to a bearing mounted housing of a pneumatic nut-running tool. The device utilizes torque reaction transmitted through the tool to the housing to cause actuation of an external push rod to operate a microswitch in a signal circuit when torque of a preset valve has been delivered to the work. As the reactionary torque in the tool is relaxed, the torque sensing device progressively automatically returns to normal condition. The tool is bearing mounted in a supporting block that is fixed to a gang-plate adapted to be held stationary. The gang-plate is adapted to carry a plurality of such tools, the torque sensing device of each of which is associated with a separate microswitch in a common signal circuit.

[ Feb. 29, 1972 United States Patent Amtsberg et al.

[54] PNEUMATIC NUT-RUNNER HAVING A 3,442,177 5/1969 TORQUE SENSINGDEVICE 3,180,612 4/1965 Primary Examiner-Emest R. PurserAttorney-Stephen Rudy [72] Inventors: Lester A. Amtsberg, Utica; WilliamK.

Wallace, Bameveld, both of NY.

[73] Assignee: Chicago Pneumatic Tool Company, New

York, NY.

[22] Filed: Apr. 13, 1970 [21] Appl.No.: 27,822

torque reaction transmitted through the tool to the housing toApplication cause actuation of an external push rod to operate aDivision of Scr. No. 788,220, Dec. 3, 1968, Pat. No. microswitch in asignal circuit when torque of a preset valve 3,538,763. has beendelivered to the work. As the reactionary torque in the tool is relaxed,the torque sensing device progressively au- "r. m 15 d u. IF

[52] U.S. Cl...

each of which is associated with a separate microswitch in a commonsignal circuit.

[56] References Cited UNITED STATES PATENTS lai t r nsi m Coates et al...,,l3/l36 X PNEUMATIC NUT-RUNNER HAVING A TORQUE SENSING DEVICEBACKGROUND OF THE INVENTION This is a division of application serialnumber 788,220 filed Dec. 31, 1968, now patent number 3,538,763 datedNov. 10, 1970.

This invention relates to the art of torque sensing devices forpneumatic nut-running tools.

The general objective is to provide a pneumatic nut-running tool with atorque sensing device, which device is operable in response toreactionary torque transmitted to the toolshousing during operation ofthe tool so as to actuate a signal circuit when the required value oftorque has been delivered to the work.

A feature of the device is that it utilizes reactionary torquetransmitted to the housing of the tool for its operation. This enablesthe device to be located externally of the tool and enables it to beapplied as a unit to the tool without modification of the usual internalmechanism of the tool.

The device may be used with an individual tool; or it may be used as aseparate attachment with each of a plurality of similar tools mountedupon a common gang-plate. In the latter application, switch componentsof the several tools may be integrated in a common control or signalcircuit.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIG. 1 is an elevational view, partially in section, of a combinedpneumatic nut-running tool and a torque sensing device embodying theinvention;

FIG. 2 is a sectional view taken on line 2-2 of FIG. 1',

FIG. 3 is a fragmentary view of the left side of FIG. 1, with someportions broken away for convenience of illustration;

FIG. 4 is an enlarged detail of the switch rod and associated mechanism;and

FIG. 5 is a detail in section of the load arm.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT In the drawing is discloseda pneumatically powered nut running tool having a general housing 11formed with a depending cylindrical tubular stem 12. The stem isjoumaled in bearings 13 and 14 mounted in a stationary open-endedsupporting block 15 whereby the housing 11 is subject to angulartumingrelative to the block. The block is bolted fast, as indicated at16, to the surface of a gang-plate 17. The gangplate, together with theblock 15, is normally held stationary during operation of the tool bymeans of an operator held handle (not shown).

Housed in a motor section 18 of the housing is a conventional rotaryair-driven motor 19, the rotor of which is bearing mounted in thehousing in usual manner for relative rotation. The rotor has a drivingconnection (not shown) with a stage of reduction gearing, generallyindicated at 20, carrying the usual idler gears, a portion of one beingshown at 21. The idler gears are meshed with a surrounding ring gear 22.The ring gear is fixed to the inner wall of a gear section 23 of thehousing. The idler gears are carried by a spindle 24 to which theytransmit the rotation of the motor. The spindle, in turn, has aninternal splined driving connection 25 with an output or work shaft 26adapted at its terminal end (not shown) to carry a wrench socket forengagement with a threaded fastener, such as a nut. Shaft 26 has abearing support in a depending tube 28 that is fixed to the gang-plate17.

Because of the mounted bearing arrangement of the housing 11 in thestationary supporting block 15, reactionary torque transmitted throughthe reduction gearing and ring gear 22 to the housing will cause angularmovement of the housing relative to the block.

A torque sensing device, generally designated 29, is operativelyassociated with the housing so as to utilize this angular movement ofthe housing to control operation of a signal circuit 31. The deviceincludes a torque or load sensing member 30 having an arm 32 extendinglaterally from a cylindrical open-ended body portion 33. The latter isfonned with internal splines with which the stem 12 of the housing has asplined driving connection 34. The body portion 33 of the sensing memberis encircled by the supporting block 15 (FIG. 2), and its load arm 32projects with some clearance, as at 35, through a longitudinal slot 36formed in the sidewall of the supporting block 15. The clearance permitslimited angular movement of the load arm 32 relative to the opposedwalls of the slot. Fixed to an external flat surface 37 of thesupporting block 15 adjacent the slot 36 is a push-rod guide block 38.The latter has an open-ended bore 39 (FIG. 3) extending transverselyrelative to the sidewall of the supporting block 15. A compressionspring 41 is seated at one end in the bore against a cover plate 42 andis seated at its other end in an annular recess 43 of the load arm 32.It biases the load arm clockwise to a normal position in abutment with arear edge 44 of slot 36, as best appears in FIG. 2.

A link or lever 45 (FIG. 3) of triangular form pivoted in a verticalslot 46 of an upper extension of the guide block 38 has a rounded comer47 abutting an upper face area of the load arm 32. The link has an upperedge underlying the bottom end of a vertically slidable pushrod 49.Seated atop the rod, as best seen in FIG. 4, is a connector 51 having anaxial bore in which the lower end of a switch rod 52 is slidablydisposed. The upper end of the switch rod slidably projects through aguide hole 53 in a rod guide 54. The latter is fixed in a switch plate55. The switch plate (FIGS. 1, 4) is supported in an elevated horizontalplane by means of a vertical rail 56. The latter is fixed at its upperend to the switch plate and is fixed at its lower end to a side of theguide block 38.

A loss-motion connection is provided between the connector 51 and theswitch rod 52 by means of a pin 57 (FIG. 4) anchored in the connectorand extending transversely through a slot 58 in the switch rod. Therodguide 54 has an enlarged coned recess 59 below its guide hole 53 inwhich a row of balls 60 are confined about the switch rod by means of anaxially slidable washer 62 under the load of a compression spring 61.The spring is limited upon a shoulder 63 of the connector and it exertsthrough the washer and balls a friction drag upon the switch rod. Theload of the spring also constantly biases the connector 51 downward sothat its pin 57 normally abuts the bottom end of slot 58 and, as aconsequence, presses the pushrod against the upper edge of link 45. Thisnormally holds the link pivoted clockwise with its rounded comer 47 incontact with the inner face of the load arm, as appears in FIG. 3. Atransverse pin 64 fixed in the projecting upper end of the switch rodnormally abuts the upper surface of the switch plate whereby theconnector is normally held downwardly under the bias of the spring so asto abut pin 57 against the bottom end of slot 58.

A microswitch 65 is supported in close axially spaced relation to thetop end of the switch rod 52. It is bolted fast to a side face of aswitch block 66 having a floating support upon a spring 67. Spring 67encircles a bolt 68 which is threadedly fixed to the switch plate 55 andextends vertically and slidably through the switch block. An adjustablenut 69 threaded upon a projecting end of the bolt may be selectivelytightened or loosened, as needed, to adjust the spaced relation of theswitch 65 to the switch rod. A guide pin 71, fixed in the switch plate55 and extending slidably up into the switch block 66 in parallelrelation to the bolt 68, restrains the switch block against relativerotation.

In summary of the operation of the torque sensing device 29, followingengagement of the socket end of the tool with the work, the motor of thetool is pneumatically started. Torque delivered during the initialoperation of the motor serves to freely run the work down to apreliminary degreeof tightness and causes during this initial phase acorresponding torque reaction through the reduction gearing 20 and thering gear 22 to the housing 11. This torque transmitted to the housingforces the load arm 32 slightly counterclockwise from its normalposition against the resistance of spring 41. This initial movement ofthe load arm pivots the control link 45 (FIG. 3) counterclockwise(broken line) to force the pushrod 49 sufficiently upward to take up theloss-motion in the loss-motion pin connection 57, 58 and to then carrythe switch rod 52 into abutment with the rnicroswitch 65. The torquereaction being transmitted from the housing through the load arm to thepushrod during this initial rundown phase of the work is insufficient tomove the switch rod sufficiently to actuate the switch to closedcondition because of the opposing force of a switch spring 72. But asthe torque delivered to the work increases, the resulting torquereaction transmitted to the housing 11 correspondingly increases toforce the load arm 32 further clockwise to move the switch rod furtherupward. When the angular travel of the load arm 32 equals the presetvalue of travel required for the pushrod 49 and switch rod 52 to closethe switch, the closed switch produces an electrical signal in thesignal circuit 31. The signal circuit indicates in suitable manner thatthe preset or required value of torque to bring the work to a finaldegree of tightness has been delivered.

The nut-running tool with which the torque sensing device 29 isassociated is of a general type. It includes the usual torque responsiveclutch (not shown) which cooperates with valve mechanism (not shown)upon delivery of the preset torque to interrupt flow of operating air tothe motor. Mechanism of this general nature is disclosed in U.S. Pat.No. 3,298,481. This action occurs concurrently with the closing actionof the rnicroswitch 65. The sudden deceleration of the motor followingshutoff of operating air decreases the applied torque so as to cause theload arm spring 41 to relax and force the load arm 32 angularlybackwards to its normal position, accordingly, as the torque of themotor is reduced. As the load arm rotates backwardly, the switch rodspring 61 expands to restore the pushrod downward. The switch rod 52does not immediately follow the return movement of the pushrod butremains elevated under the friction drag developed by the balls 60 tohold the switch closed. The switch rod is held briefly in this actuatedcondition until the loss-motion pin 57 is carried by the pushrod andconnector to the bottom of the slot 58. Further return movement of thepushrod then causes the switch rod to be drawn by the connector awayfrom the switch to allow the latter to reopen under the force of itsreturn spring 72. The brief time delay obtained by means of thelossmotion connection during which the switch remains closed is designedto allow the usual relay (not shown) in the signal circuit 31 sufficienttime to respond to the signal produced upon closing of the switch.

It is understood that the gang-plate is adapted to carry a plurality ofthe above described tools, and that a separate rnicroswitch 65individual to a separate torque sensing device 29 associated with eachtool would be integrated in the signal circuit.

The sensing device 29, as illustrated, shows only one switch but anotherswitch can be added so that a certain minimum value as well as a maximumvalue of torque applied to the faster can be indicated by the signalcircuit.

What is claimed is:

1. A nut-running tool comprising a housing, a stationary blocksupporting the housing for relative rotation, motordriven gearing in thehousing having an output spindle and having a ring gear fixed to thehousing so that torque of the gearing is transmitted to both the housingand the spindle in a particular direction, a torque arm fixed to thehousing and extending laterally therefrom, a signal circuit controlswitch, a bracket supporting the switch to the block, and loss-motionlinkage means arranged between the switch and the torque arm adaptedupon an initial predetermined angular movement of the torque arm in saiddirection to take up the loss-motion in the linkage and adapted uponsubsequent further predetermined angular movement of the torque arm tocause actuation of the switch, wherein the loss-motion linkagecomprises: a

gushrod slidable in the bracket, a lever pivoted in the bracket avingone end abutting the torque arm and having an edge underlying a bottomend of the pushrod, a switch rod slidable in the bracket disposed inaxial alignment with the switch and with the pushrod, the pushrod havinga loss-motion connection with the switch rod arranged so that upon apredetermined initial angular movement of the torque arm the pushrod iscaused to move relative to the switch rod until the loss-motion is takenup and upon subsequent further angular movement of the torque arm thepushrod and switch rod are caused to move as a unit relative to theswitch.

2. A nut-running tool as in claim 1, wherein yieldable spring meansdisposed between the torque arm and the stationary block normallyresists angular movement of the torque arm in said direction.

3. A nut-running tool as in claim 1, wherein the loss-motion connectionis defined by means of a pin in the pushrod operable in a slot of theswitch rod, and a spring load encircling the switch rod biasing thepushrod away from the switch rod into abutment with the lever.

4. A nut-running tool as in claim 1, wherein manipulative means isprovided for selectively effecting adjustment of the spacing of theswitch relative to the switch rod.

1. A nut-running tool comprising a housing, a stationary blocksupporting the housing for relative rotation, motor-driven gearing inthe housing having an output spindle and having a ring gear fixed to thehousing so that torque of the gearing is transmitted to both the housingand the spindle in a particular direction, a torque arm fixed to thehousing and extending laterally therefrom, a signal circuit controlswitch, a bracket supporting the switch to the block, and loss-motionlinkage means arranged between the switch and the torque arm adaptedupon an initial predetermined angular movement of the torque arm in saiddirection to take up the loss-motion in the linkage and adapted uponsubsequent further predetermined angular movement of the torque arm tocause actuation of the switch, wherein the lossmotion linkage comprises:a pushrod slidable in the bracket, a lever pivoted in the bracket havingone end abutting the torque arm and having an edge underlying a bottomend of the pushrod, a switch rod slidable in the bracket disposed inaxial alignment with the switch and with the pushrod, the pushrod havinga lossmotion connection with the switch rod arranged so that upon apredetermined initial angular movement of the torque arm the pushrod iscaused to move relative to the switch rod until the loss-motion is takenup and upon subsequent further angular movement of the torque arm thepushrod and switch rod are caused to move as a unit relative to theswitch.
 2. A nut-running tool as in claim 1, wherein yieldable springmeans disposed between the torque arm and the stationary block normallyresists angular movement of the torque arm in said direction.
 3. Anut-running tool as in claim 1, wherein the loss-motion connection isdefined by means of a pin in the pushrod operable in a slot of theswitch rod, and a spring load encircling the switch rod biasing thepushrod away from the switch rod into abutment with the lever.
 4. Anut-running tool as in claim 1, wherein manipulative means is providedfor selectively effecting adjustment of the spacing of the switchrelative to the switch rod.